Strange that nobody noticed, but DMG_SLASH triggers the corresponding hit sound. Especially it's annoying when interval is set to defaults 0.5s. It's better to change the damage type to DMG_ACID, as it accurately represents the damage caused by the tongue in Versus mode, and it doesn't produce any sounds. Also, the damage in the game typically depends on the current difficulty level, so using a static value is not the correct approach. In VS damage is 3, and as far as I know, VS mode generally corresponds to the coop difficulty level set to Hard in terms of damage. The damage interval in VS is 1.0625 seconds, if we aim for an exact replication
I read that you are currently don't have time. Since I've already made the changes for myself, I'm sharing this version of the plugin.